Sulfiphilic Few‐Layered MoSe₂ Nanoflakes Decorated rGO as a Highly Efficient Sulfur Host for Lithium‐Sulfur Batteries

Abstract

Lithium‐sulfur batteries (LSBs) have been regarded as a competitive candidate for next‐generation electrochemical energy‐storage technologies due to their merits in energy density. The sluggish redox kinetics of the electrochemistry and the high solubility of polysulfides during cycling result in insufficient sulfur utilization, severe polarization, and poor cyclic stability. Herein, sulfiphilic few‐layered MoSe2 nanoflakes decorated rGO (MoSe2@rGO) hybrid has been synthesized through a facile hydrothermal method and for the first time, is used as a conceptually new‐style sulfur host for LSBs. Specifically, MoSe2@rGO not only strongly interacts with polysulfides but also dynamically strengthens polysulfide redox reactions. The polarization problem is effectively alleviated by relying on the sulfiphilic MoSe2. Moreover, MoSe2@rGO is demonstrated to be beneficial for the fast nucleation and uniform deposition of Li2S, contributing to the high discharge capacity and good cyclic stability. A high initial capacity of 1608 mAh g−1 at 0.1 C, a slow decay rate of 0.042% per loop at 0.25 C, and a high reversible capacity of 870 mAh g−1 with areal sulfur loading of 4.2 mg cm−2 at 0.3 C are obtained. The concept of introducing sulfiphilic transition‐metal selenides into the LSBs system can stimulate engineering of novel architectures with enhanced properties for various energy‐storage devices.

A Nanocomposite of Si@C Nanosphere and Hollow Porous Co9S8/C Polyhedron as High‐Performance Anode for Lithium‐Ion Battery

“…The spectra are consisted of a semicircle at the high‐ to medium‐frequency region and an inclined straight line at the low‐frequency region. According to previous literature, the semicircle belongs to the resistance of SEI film ( R SEI ) and the charge‐transfer resistance ( R ct ), [43,44,45] and the straight line can be assigned to the lithium ion diffusion in electrodes, known as the Warburg impedance ( Z w ) [46,47,48] . As shown in Figure 6a, in comparison to Si@C anodes, the Si@C−Co 9 S 8 /C anodes show the relative lower R ct , suggesting high electrical conductivity of the Si@C−Co 9 S 8 /C anodes.…”

“…According to previous literature, the semicircle belongs to the resistance of SEI film (R SEI ) and the charge-transfer resistance (R ct ), [43,44,45] and the straight line can be assigned to the lithium ion diffusion in electrodes, known as the Warburg impedance (Z w ). [46,47,48] As shown in Figure 6a, in comparison to Si@C anodes, the Si@CÀ Co 9 S 8 /C anodes show the relative lower R ct , suggesting high electrical conductivity of the Si@CÀ Co 9 S 8 /C anodes. Therefore, Si@CÀ Co 9 S 8 /C anodes display dramatically enhanced electrochemical performance, which can be ascribed to the rational structural design of Si@CÀ Co 9 S 8 /C.…”

Emerging Catalysts to Promote Kinetics of Lithium–Sulfur Batteries

“…[ 88 ] For example, our group demonstrated that MoSe 2 @rGO can provide faster LiPSs conversion kinetics than rGO by comparing their i 0 values calculated from Tafel plots ( Figure 7 a). [ 89 ]…”

“…Transition metal selenides with moderate electronegativity differences between transition metals and selenium as well as the variable oxidation state of selenium possess superior catalytic effect and therefore attract tremendous attention for energy storage (such as sodium‐ion battery anodes, solar cells, photocatalysis, and HER process) in recent years. In addition, compared with sulfides, selenides exhibit higher conductivity (1 × 10 −3 S m −1 vs 5 × 10 −28 S m −1 ) which was usually employed to form selenium–sulfur solid solutions for compensating the inferior conductivity and stiff activity of S. [ 89,122 ] Despite these merits, the researches of metal selenides in the Li–S systems especially served as catalytic materials is still at its early stage.…”

Polar, catalytic, and conductive CoSe2/C frameworks for performance enhanced S cathode in Li–S batteries

“…All these features suggest the metal selenides could be good candidates to enhance the performances of S cathode by mitigate the polysulfides shuttle effect by chemically adsorb the polysulfides and catalytic acceleration of redox kinetics. Recently, several creative studies were reported for the successful applications of metal selenides' in Li-S batteries [34][35][36][37] .…”